There are 3 types of dominance: Directional, Sensory and Oculomotor (0.3 Ocular Dominance), and there is no reason to assume that, for any individual, the same side will be dominant for all 3 categories.

Tests for both sensory and directional dominance, found that the dominance type was not always the same in many of the subjects tested. It is possible that a personÃ­s dominance can change depending on the fixation distance (far vs. near, etc.), or for different visual tasks.

The degree of dominance can also vary from person to person. Some people may be strongly dominant in one eye; some people have a nearly equal preference for either eye, and some people may freely alternate dominance between the two eyes.

Note: I believe that persons with non-specific dominance, focus more on things at their left- and right side, because it's harder to focusing strait in front or visa versa. By reducing their peripheral view with glasses or such, the will have to change to "a view" with one dominant side to avoid parallax. But this is unnatural for them (at first or always?) and it will change the motor system of their eyes, and the way the persons brain works (thinks) from the peripheral visual system, more to the central visual system. One has to be careful when physically changing one's view.

In nature our visual system is based upon a 3-dimensional space
but when it comes to reading our view is focused on a flat, non-depth
environment. A reader has to focus on small detailed letters and words in front,
reducing his/her peripheral-view and shut him/herself off their
environment full of sounds, colors, shapes, movement, etc. and reproduce the sounds of the words in his/her head.

It also can cause them to shift their natural dominance from left to
right; the 'over-focusing' stops the
natural 'flow' from one (text) element to the next. The ocular dominance system can get out of balance, shifting focusing from detail to global (0.1 Left and right brain: function & interaction and 0.3.1 Ocular Dominance ) creating visual disturbances and a blurry sight.

The Hermann-grid illusion,
gives a good reflection of this shifting, balance seeking activity.
When we look at the image above, our focus shifts from the whole image
that is black and look for a point/detail at a crossing point of lines,
this activity goes back and forth, also trying to get 'visualization',
understanding of the grid itself, who is white in contrast to the black
square. This non grip having situation starts to pop-up the blurry
points and confusion in our brain.

To overcome this unbalanced brain activity, that causes visual stress, there are exercises to find 'peace of mind' (16. Peace of Mind).
By letting go to 'sharply' focus on the text and rather just flow
(gaze) over it, they can stop these grip/balance seeking movements and
improve their reading ability, some of these exercises are:

Body movement
exercises like juggling balls creating a stronger balance on one side
al-thus finding an inner-peace, when juggling one learns to focus on
the global-ball-movement, and shutting him/herself of from their
environment, no longer trying to follow the different ball's. (Juggling article )

The use of colors,
text is written in colors because they are not based upon alignment
(see rods & cones) training de dyslectic to the reading rhythm,
flowing over the text instead of trying to sharply focus.